Compaq Presario CQ57-229WM SUPERIOR GRADE Tech Rover Brand 9-Cell (High-Capacity) Laptop Battery 100% Compatible - Will not void your original laptop warranty Tech Rover&trade; Quality product with 30-DAY Worry-Free Return Policy Brand New Battery, 6600 - 7800 mAh, Effective Capacity All Tech Rover&trade; branded items carry a 1 year warranty against manufacturer defects. 9-Cell [Extended-Capacity] Battery *Comfortable fit: A natural and comfortable angle elevates your notebook for easier typing. Improved wrist posture promotes more relaxed working conditions and also for better heat dissipation